Color diffusion transfer processes and elements comprising auxiliary developers or their precursors

ABSTRACT

IMPROVED MINIMUM PRINT DENSITIES ARE PRODUCED IN COLOR DIFFUSION TRANSFER SYSTEMS BY PROCESSING IN THE PRESENCE OF A LACTONE DERIVATIVE SILVER HALIDE DEVELOPING AGENT, SUCH AS A COUMARIN DERIVATIVE, WHICH HAS THE PROPERTY OF FORMING A LACTONE DEVELOPING AGENT PRECURSOR UNDER ACID, NEUTRAL AND SLIGHTLY ALKALINE CONDITIONS.

United States Patent US. Cl. 963 28 Claims ABSTRACT OF THE DISCLOSURE Improved minimum print densities are produced in color diffusion transfer systems by processing in the presence of a lactone derivative silver halide developing agent, such as a coumarin derivative, which has the property of forming a lactone developing agent precursor under acid, neutral and slightly alkaline conditions.

This invention relates to the art of photography and more particularly to a multicolor diffusion transfer process in photography and materials adapted for use in the process.

A diffusion transfer color process has been described in a number of patents, including US. Patent 2,983,606, werein photographic elements containing silver halide emulsion layers and layers containing ditfusible dye developers (dyes having a silver halide developing function) are exposed to record the latent image in the silver halide and then treated with an alkaline processing composition which permeates the emulsion layers and layers containing the dye developers which then develop the latent images to silver images. At the same time, oxidation products of the dye developers are formed in situ with the silver images and which are relatively nondiffusing in the colloid vehicle of the layers.

The nondifiusing character of the oxidized dye developers is apparently due at least in part to a decrease in solubility in the alkaline processing liquid, and may also be due to a hardening effect of the oxidized developer upon the colloid vehicles of the layers which retards the diifusion of the oxidized dye developers. The residual unoxidized dye developers remaining in the layers in imagewise distribution are transferred by diffusion to a superposed reception element substantially to the exclusion of the silver image and oxidized dye developer to provide a positive dye image.

When an element containing differentially sensitized silver halide emulsion layers is used and substractively colored dye developers are present in or contiguous to the respective emulsion layers, upon treatment with the processing liquid the dye developers are oxidized and renderednondiffusing in the developed regions of the layers and the residual dye developer images in the positive regions are transferred by diffusion and in register to the reception element to provide a multicolor reproduction.

As is apparent, the success of the process depends in part upon the extent to which the dye developers in the exposed (negative) regions of the emulsion layers have been rendered substantially nondiffusing in the development reaction. Thus, if a quantity of unoxidized dye developer remains in a fully exposed negative region corresponding to the highlights of the subject, it will be transferred to the reception layer along with the unreacted dye developer in the positive regions and appears as high minimum density on the resultant color print. Typical dye developers such as l,4-bis[,B-(2,5-dihydroxy- "ice phenyl)-ethylamino]-anthraquinone are relatively weak silver halide developing agents even when used at the comparatively high pH of the order of 13 required in the process and do not rapidly develop the emulsions to obtain dye images having the full scale of density and contrast expected with conventional developing agents. As a result, color prints obtained in the processes may exhibit an undesirable high minimum density in the highlight regions, low color saturation, contrast and density and poor color separation. Therefore, it has been desirable to employ various compounds as auxiliary silver halide developing agents which increase the quality of the resultant color print. In the past, these compounds included 3-pyrazolidones, Metol (mono-N-methyl-paminophenol), 2,4diaminophenol, and 4-methylphenylhydroquinone. The use of such compounds has improved print densities and color saturation, however, attempts to decrease minimum density and lower stain have resulted in undesirable low contrast and low maximum density.

A further problem with known auxiliary developers, sometimes referred to as acid-quenchable auxiliary developers, is that they have the property of decreasing development time in the presence of a development activator (approximate pH 13.0) but when the desired degree of development is reached, the developing action must be quenched by employing strong acidic compounds to reduce the pH to 6.0 or lower. It would be desirable to stop development without having to employ strong acidic compounds.

U.S. Patent 2,983,606 suggests in column 20, lines 39- end, column 21 and column 22, lines 1-44 the use of auxiliary silver halide developing agents in diffusion transfer processes employing dye developers, but does not teach the particular auxiliary developing agents of this invention or the unexpected results obtained from the use thereof. US. Patent 3,146,102 also teaches the use of auxiliary silver halide developing agents such as the hydroquinones, e.g., 4'-methylphenylhydroquinone, in dilfusion transfer processes employing dye developers, but again does not teach or suggest applicants invention, U.S.S.R. Patent 150,009 issued Sept. 16, 1962 (Chemical Abstracts, volume 58, p. 4086e), British Patent 767,701 and French Patent 1,349,658 disclose coumarins utilized in photographic materials but do not teach applicants invention 7 relating to color diffusion transfer systems and the results which are unexpectedly obtained.

It is therefore an object of my invention to provide novel color diffusion transfer materials with pH-sensitive auxiliary silver halide developing agents that are capable of being quenched under neutral or slightly alkaline conditions, i.e., less than pH 9.0.

A further object of my invention is to provide a novel process for the production of a multicolor dilfusion transfer image having improved minimum densities when compared to prior art acid-quenchable auxiliary developers.

These and other objects are achieved in accordance with the present invention whereby color diffusion trans fer processes are conducted in the presence of an auxiliary silver halide developing agent which is a lactone derivative silver halide developing agent which has the property of forming a lactone developing agent precursor under acid, neutral and slightly alkaline conditions, e.g., a pH about 9 or below and/ or a lactone silver halide developing agent precursor which has the property of forming a lactone derivative silver halide developing agent in the presence of an alkaline development activator.

In particular, this invention relates to a photographic film unit which is adapted to be processed by passing said 3 unit between a pair of juxtaposed pressure-applying members comprising:

said film unit containing as an auxiliary silver halide developing agent a lactone developing agent precursor or a lactone derivative silver halide developing agent which has the property of forming a lactone developing agent precursor under acid, neutral and slightly alkaline conditions; said rupturahle container being adapted to be posi tioned-so that a compressive force applied to said container by said pressure-applying members will elfect a discharge of the containers contents into said film unit.

The dye image-receiving layer can be'located on a separate support adapted to be superposed on the photosensitive element after exposure thereof. Such image-reoeiving elements are disclosed, for example, in US. Patent 3,362,819. The rupturable container is usually positioned in relation to the photosensitive element and the image-receiving element so that a compressive force applied to the container by the pressure-applying members will efiect a discharge of the containers contents between the image-receiving element and the outermost layer of the photosensitive element. The dye image-receiving layer can also be located integral with the photosensitive element between the support and the lowermost photosensi tive silver halide emulsion layer. Such integral receivernegative photosensitive elements are'disclosed, for example, in 13.8. Patent 3,415,644 and useful in camera apparatus of the type disclosed in Belgian Patents ll-8,553 and 718,554. Another embodiment of an integral receivernegative photosensitive element in which the instant in-- vention may be employed is described in US. Patent 2,983,606, column '14, lines 27-55. In such an integral receiver-negative photosensitive element, a stripping layer may be employed between the image-receiving layer and the adjacent photosensitive layer to facilitate removal of the image-receiving layer therefrom. Alternately, the photosensitive layers maybe unhardened so that they can be removed by merely washing them ofi the receiver with hot water. Since the image-receiving layer in this case would have to be hardened with, for example, an aldehyde hardener, the photosensitive layers of the integral unit would preferably contain an aldehyde hardener scavenger, such as semicarbazide hydrochloride, to prevent them from becoming hardened and thus unremovable by washing oil.

A wide range of lactone derivative silver halide devel oping agents which have the property of forming a lactone silver halide developing agent precursor under acid, neutral and slightly alkaline conditions can be employed according to the invention. These include any lactone derivatives which provide the desired developing activity and improved minimum densities without adversely afiecting photographic speed and other desired sensitometric properties. Suitable lactone derivative developing agents include those which under neutral, slightly alkaline or acid conditions, i.e., when the pH is lowered to a level of I about 9 or lower, i.e., about 2 to about 9, do not have significant developing activity, if any, due to formation of a developing agent precursor.

' The mechanism involved is believed to be the opening and closing of any .anhydro ring in lactone compounds depending on pH conditions. For instance, in the case of a G-hydroxy coumarin and/or fi-amino coumarin developing agent precursor, under alkaline conditions such as at a pH of about 10 to about 14, the anhydro ring of such a lactone is believed to open to ning a cinnamic acid developing agent, Le, a coumarin derivative develop- 4 ing agent. This cinnamic acid developing agent has good developing properties and forms oxidation products which provide very little or no stain.

A wide variety of hydroxy cinnamic acid and/or amino cinnamic acid developing agents can be employed in the instant invention. Especially suitable developing agents are derivatives of 6-hydroxy coumarins, 6-amino coumarins, mixtures thereof and their salts, e.g., water soluble salts. Suitable cinnamic acid developing agents which can be employed in the invention include compounds of the formula:

(a) R and R are each hydrogen, halogen, e.g., chlorine,

. bromine, or iodine; or alkyl, e.g., alkyl containing 1 to.

5 carbon atoms such as methyl, ethyl, propyl, butyl and pentyl;

(b) R and R are each hydrogen, alkyl, e.g., alkyl containing 1 to 5 carbon atoms such as methyl, ethyl, propyl, butyl and pentyl; alkoxy, e.g., alkoxy containing 1 to 5 carbon atoms such as methoxy, ethoxy, propoxy, butoxy and pentoxy; halogen, as described above or aryl, e.g., aryl containing up to20 carbon atoms, such as phenyl, tolyl and xylyl;

(c) R and R are each hydroxy, hydrogen, amino, i.e., NH NHR or NRR' wherein R and R are alkyl containing 1 to 5 carbon atoms, such as methyl, ethyl, butyl and pentyl; alkyl containing 1 to 5 carbon atoms, as described above, alkoxy containing 1 to 5 carbon atoms, as described above, or aryl, e.g., aryl containing up to 20 carbon atoms such as phenyl, tolyl, xylyl;

mixtures thereof, and their salts, e.g. acid salts such as chloride, hydrochloride and sulfate salts and alkali metal salts such as potassium and sodium salts. Water soluble salts are also uitable, a mentioned above.

Suitable cinnamic acid developing agents which can be employed in the instant invention include:

' 2,5 -dihydroxy-3 ,4,6 trimethyl cinnamic acid; and

2,3-dihydroxy cinnamic acid.

Similarly, corresponding derivatives of lactone developing agent precursors can be employed, which are derivatives of lactones containing a S-membered anhydro ring rather than a G-membered anhydro ring as in coumarins. These include, for example, derivatives which are developing agents of the formula:

l R4 C-C O OH Rs- OH I lit wherein R R R R R and 'R are as described for Structure (I). Examples of developing agents within Structure (II) include:

and

CH2-COOH Also included are compounds which are derivatives of 3,4- dihydrocoumarins. These include compounds of the formula:

III R 9 2 1 wherein R R R R R and R are as described for Structure (1). Examples of compounds within Structure (III) include:

A wide range of lactone silver halide developing agent precursors can be employed in the instant invention which have the property of forming a lactone derivative silver halide developing agent in the presence of an alkaline development activator, e.g., under alkaline conditions including a pH of about 10 to 14, typically a pH of about 12-14. Suitable lactone developing agent precursors include any lactones which in the presence of an alkaline development activator have the property of forming a lactone derivative silver halide developing agent, typically, it is believed by opening of the anhydro ring of the lactone, and in the presence of such a development activator provide desired developing activity and improved minimum densities without adversely affecting photographic speed and other desired sensitometric properties.

Suitable hydroxy coumarins and amino coumarins which are developing agent precursors which can be employed in the instant invention include developing agent precursors of the formula:

(IV) l a l a I \O u wherein R R R R R and R are as described for Structure (1).

Suitable amino coumarins and/or hydroxy coumarins which, for example, can be employed in my invention include:

8-hydroxy coumarin; 6-hydroxy-5,7-dimethoxy coumarin; 6-hydroxy-4,7-dimethyl coumarin; 6-hydroxy-5,7-diethoxy-4-methyl coumarin; 6-hydroxy coumarin; 8-hydroxy-4-methyl coumarin; 6-hydroxy-4-methyl coumarin; 6-hydroxy-7-methoxy-4-methyl coumarin; 7-(benzyloxy)-6-hydroxy coumarin; 6-hydroxy coumarin-S-sulfonic acid; 6-hydroXy-2-keto-1,4-benzoxathian 6-hydroxy coumarin-S-sulfinic acid; S-hydroxy coumarin-Z-one 4,6-dihydroxy coumarin; 8-amino coumarin; 6-amino coumarin; 6-amino-5,7-dimethoxy coumarin; 6-amino-4,7-dimethyl coumarin; 8-amino-4-methyl coumarin; 6-amino-5,7-diethoxy-4-methyl coumarin; 6-amino-8-hydroxy coumarin; 6-hydroxy-8-amino coumarin and the like.

Other suitable lactone silver halide developing agent precursors which can be employed include those containing a S-membered anhydro ring. These include, for example, lactones which are developing agent precursors of the formula:

wherein R R R R and R are as described for Structure (1), with the exception that R can also be aryl, as described, especially phenyl, tolyl or xylyl. Examples of developing agent precursors within Structure (1V) include:

HaC(CH2)1 O and Other suitable lactone developing agent precursors include 3,4-dihydrocoumarin developing agent precursors corresponding to the coumarin developing agent precursors of Structure (IV). Examples of 3,4dihydrocoumarin developing agent precursors include:

6,7-dihydroxy-4-methyl-3,4-dihydrocoumarin and 7,=8-dihydroxy-4-methyl-3,4-dihydrocoumarin.

The developing agents and/ or developing agent precursors which can be employed in this invention may be located in difierent positions in a diffusion transfer film unit. For example, they can be employed in one or more layers of the photosensitive element and/ or in the processing composition, if desired.

The lactone derivative developing agent employed in this invention is preferably selected from coumarin derivatives, mixtures thereof, and their salts, e.g., cinnamic acid developing agents within Structure (1), especially derivatives of 6-hydroxy coumarins, 6-amino coumarins, mixtures thereof, and the r salts.

Upon treatment with an alkaline activator, it is believed the lactone ring of the described coumarin compounds, for example, opens to yield a hydroxy group and thus a strong developer. The developing action can be stopped, or returned to its initial precursor form, which in some cases can possess a weak developing capacity, by returning the developing agent form to the developing agent precursor form by treatment with an acid, e.g., usually a mild acidic solution, such as an aqueous acetic acid or carbonic acid or by employing a polymeric acid layer in the receiver or photosensitive element. This property is referred to as acid quenching and is especially useful in photographic processes where residual oxidation or developer activity is undesirable. The foregoing relationship or reaction can be illustrated by the following equation employing coumarins as an example:

coumarin form cinnamic acid form a Ra developer precursor developing agent wherein R R R R R and R are as described for Structure (1).

In order to obtain the desired developing action in a diffusion transfer system upon conversion to the cinnamic acid form the coumarin preferably has a hydroxy group or an amino group or a derivative of these groups which is in the 6 position {i.e., R and/or 8 position (i.e., R i.e., located para or ortho, in the cinnamic form, to the unblocked hydroxy group,

The concentrations of the auxiliary developing agents and/or developing agent precursors employed in the practice of this invention can vary over a wide range depending upon the particular photographic and physical variables present in the system, for example, the position of the developing agent and/or developing agent precursors in the photosensitive element, the alkaline processing composition, the desired image, etc. Generally speaking, the auxiliary developing agents and/or precursors may be employed in a concentration of from about 0.1 to about 1,000, preferably 1 to 100, mg. per gram of processing composition.

Other details concerning lactone derivative silver halide developing agents and lactone developing agent precursors, details of their preparation, and their functioning in photographic systems in general may be found in my co-worker, Edwin N. Oftedahls copending applications Ser. Nos. 764,301 and 764,358 both filed Oct. 1, 1968.

The film assembly of my invention can be used to produce positive images in single or multicolors. In a three-color system, each silver halide emulsion layer of the film assembly of my invention will have associated therewith a dye image-providing material processing a spectral absorption range substantially complementary to the predominant sensitivity range of its associated emulsion, i.e., the blue-sensitive silver halide emulsion layer will have a yellow dye image-providing material associated therewith, the green-sensitive silver halide emulsion layer will have a magenta dye image-providing material associated therewith, and the red-sensitive silver halide emulsion layer will have a cyan dye image-providing material associated therewith. The dye image-providing material associated with each silver halide emulsion layer may be contained either in the silver halide emulsion layer itself or in a layer contiguous to the silver halide emulsion layer.

Spectral sensitizing dyes can be used conveniently to confer additional sensitivity to the light sensitive silver halide emulsion of the multilayer photographic elements of the invention. For instance, additional spectral sensitization can be obtained by treating the emulsion with a solution of a sensitizing dye in an organic solvent or the dye may be added in the form of a dispersion as described in Owens et al. British Patent 1,154,781. For optimum results, the dye may either be added to the emulsion as a final step or at some earlier stage.

sensitizing dyes useful in sensitizing such emulsions are described, for example, in Brooker et a1. U.S. Patent 2,526,632, issued Oct. 24, 1950; Sprague U.S. Patent 2,503,776, issued Apr. 11, 1950; Brooker et al. U.S. Patent 2,493,748; and Taber et al. U.S. Patent 3,384,486. Spectral sensitizers which can be used include the cyanines, merocyanines, complex (tri or tetranuclear) merocyanines, complex (tri or tetranuclear) cyanines, holopolar cyanines, styryls, hemicyanines (e.g. enamine hemicyanines), oxonols and hemioxonols.

Dyes of the cyanine classes may contain such basic nuclei as the thiazoliues, oxazolines, pyrrolines, pyridines, oxazoles, thiazoles, selenazoles and imidazoles, Such nuclei may contain alkyl, alkylene, hydroxyalkyl, sulfoalkyl, carboxyalkyl, aminoalkyl and enamine groups and may be fused to carbocyclic or heterocyclic ring systems either unsubstituted or substituted with halogen, phenyl, alkyl, haloalkyl, cyano, or alkoxy groups. The dyes may be symmetrical or unsymmetrical and may contain alkyl, phenyl, enamine or heterocyclic substituents on the methine or polymethine chain.

The merocyanine dyes may contain the basic nuclei mentioned above as well as acid nuclei such as thiohydantoins, rhodanines, oxazolidenediones, thiazolidenediones, barbituric acids, thiazolineones, and malononitrile. These acid nuclei may be subsituted with alkyl, alkylene, phenyl, carboxyalkyl, sulfoalkyl, hydroxyal'kyl, alkoxy alkyl, alkylamino groups, or heterocyclic nuclei. Combinations of these dyes may be' used, if desired. In addition, supersensitizing addenda which do not absorb visible light may be included for instance ascorbic acid derivatives, azaindenes, cadmium salts, and organic sulfonic acids as described in McFall et al. U.S. Patent 2,933,390 and Jones et al. U.S. Patent 2,937,089.

The various silver halide emulsion layers of a color film assembly of my invention can be disposed in the usual order, i.e., the blue-sensitive silver halide emulsion layer first with respect to the exposure side, followed by the green-sensitive and red-sensitive silver halide emulsion layers. If desired, a yellow dye layer or a Carey Lea silver layer can be present between the blue-sensitive and greensensitive silver halide emulsion layer for absorbing or filtering blue radiation that may be transmitted through the blue-sensitive layer. If desired, the selectively sensitized silver halide emulsion layers can be disposed in a different order, e.g., the red-sensitive layer first with respect to the exposure side, followed by the greensensitive and bluesensitive layers.

Any dye image-providing material can be employed in the film unit of my invention as long as an imagewise distribution of the material will be formed after development as a function of the imagewise exposure of the silver halide emulsion to which the dye image-providing rnaterial is associated. Particularly good results are obtained when the dye image-providing materials are dye developers, i.e., compounds which contain in the same mole cule both the chromophoric system of a dye and also a silver halide developing function. A preferred silver halide developing moiety in such dye developers is a hydroquinonyl group. Dye developers and their functioning in color diffusion transfer systems are well known in the art as shown, for example, by U.S. Patent No. 2,983,606 and the various United States applications listed in column 27 of that patent. Other patents disclosing dye developers useful in the present invention are U.S. Patents Nos: 2,992,106; 3,047,386; 3,076,808; 3,076,820; 3,077,- 402; 3,126,280; 3,131,061; 3,134,762; 3,134,765; 3,135,- 604; 3,135,605; 3,135,606; 3,135,734; 3,141,772; and 3,142,565. When dye developers are employed as the dye image-providing materials in the film assembly of this invention, an alkaline processing or activating solution is conveniently employed in the rupturable container or pod. After exposure of the element, the alkaline processing solution is released from the pod to permeate the emulsion layers and initiate development of the latent images contained therein. The dye developers are immobilized in exposed areas as a consequence of the development of the latent images. This immobilization is due at least in part to a change in the solubility characteristics of the dye developers upon oxidation. In unexposed areas of the emulsion layers, the dye developers remain difiusible and thus provide imagewise distributions of unoxidized dye developer dissolved in the liquid processing composition as a function of the point-to-point degree of exposure of the silver halide emulsion layers. At least part of these imagewise distributions of unoxidized dye developer are transferred, by diffusion, to the image-receiving layer. The image-receiving layer contains materials adapted to mordant or otherwise fix the diffused, unoxidized dye developers.

Good results are obtained when dye-developers are employed in separate layers contiguous to each silver halide emulsion layer. Such layers can be applied by using coating solutions containing about 0.5 to about 8%, by weight, of the dye developer distributed in a hydrophilic filmforming natural material or synthetic polymer such as gelatin, polyvinyl alcohol, etc., which is adapted to be permeated by aqueous alkaline processing composition.

In addition to conventional techniques for the direct dispersion of a particulate solid material in a polymeric or colloidal matrix such as ball-milling and the like techniques, the preparation of the dye developer dispersion can also be obtained by dissolving the dye developer in an appropriate solvent or mixture of solvents, dispersing the resultant solution in the polymeric binder, with op tional subsequent removal of the solvent or solvents employed. Further details concerning these dispersing techniques and the solvents employed are found, for example, in U.S. Patents Nos. 2,269,158; 2,322,027; 2,304,939; 2,304,940; 2,801,171, etc.

Other dye image-providing materials which can be employed in this invention include coupling dyes as disclosed, for example, in U.S. Patent 3,087,817, shifted or colorless dye developers as disclosed, for example, in U.S. Patent 3,230,085, dye developer-precursors, dye-precursor developers, metal-dye complexes as disclosed, for example, in U.S. Patent 3,185,567 and U.S. Patent 3,453,- 107, nondiffusible couplers as disclosed in U.S. Patents 3,227,550 and 3,227,551, couplers requiring an oxidizing agent in the image-receiving layer in order to form colors, ring-closing dye developers as disclosed in U.S. Patent 3,443,943, color providing materials as disclosed in U.S. Patents 3,443,940 and 3,443,941, etc. These dye imageproviding materials can be incorporated into the photosensitive element in the same manner listed above for dye developers.

In a color film unit according to the invention, each silver halide emulsion layer containing a dye image-providing material or having the dye image-providing material present in a contiguous layer may be separated from the other silver halide emulsion layers in the film unit by materials including gelatin, calcium alginate, or any of 10 those disclosed in U.S. Patent No. 3,384,483, polymeric materials such as polyvinylamides as disclosed in U.S. Patent 3,421,892, or any of those disclosed in U.S. Patents Nos. 2,992,104; 3,043,692; 3,044,873; 3,061,428; 3,069,- 263; 3,069,264; 3,121,011; and 3,427,158.

Generally speaking, except where noted otherwise, the silver halide emulsion layers in the invention comprise photosensitive silver halide dispersed in gelatin and are about 0.6 to 6 microns in thickness; the dye image-providing materials are dispersed in an aqueous alkaline solution-permeable polymeric binder, such as gelatin, as a separate layer about 1 to 7 microns in thickness; and the alkaline solution-permeable polymeric interlayers, e.g., gelatin, are about 1 to 5 microns in thickness. Of course, these thicknesses are approximate only and can be modified according to the product desired.

Any material can be employed as the image-receiving layer in this inventionas long as the desired function of mordanting or otherwise fixing the dye images will beobtained. The particular material chosen will, of course, depend upon the dye image to be mordanted. If acid dyes are to be mordanted, the image-receiving layer can contain mordants such as polymers of amino guanidine derivatives of vinyl methyl ketone such as described in the Minsk U.S. Patent 2,882,156 granted Apr. 14, 1959. Other mordants useful in my invention include the 2- vinyl pyridine polymer metho-p-toluene sulfonate and similar compounds described in Sprague et al. U.S. Patent 2,484,430 granted Oct. 11, 1949, and cetyl trimethylammonium bromide, etc. Effective mordanting compositions are also described in Whitmore U.S. Patent 3,271,148 and Bush U.S. Patent 3,271,147. Furthermore, the imagereceiving layer can be sufficient by itself to mordant the dye as in the case of use of an alkaline solution-permeable polymeric layer such as N-methoxymethyl polyhexylmethylene adiparnide; partially hydrolyzed polyvinyl acetate; polyvinyl alcohol with or without plasticizers; cellulose acetate; gelatin; and other materials of a similar nature. Polyvinyl alcohol or gelatin containing a dye mordant such as poly-4 vinylpyridine as disclosed in U.S. Patent 3,148,061 can also be employed in my invention for mordanting dye developers. Generally, good results are obtained when the image-receiving layer is from about 0.25 to about 0.04 mil in thickness. This thickness, of course, can be modified depending upon the result desired. The image-receiving layer can also contain ultraviolet absorbing materials to protect the mordanted dye images from fading due to ultraviolet light.

Use of a polymeric acid layer, as disclosed in U.S. Patent 3,362,819, in the film unit of the invention will enhance the results obtained. Generally, the polymeric acid layer will effect a reduction in the pH of the image layer from about 13 or 14 to at least 11 and preferably 5-8 within a short time after imbibition. Such polymeric acids reduce the pH of the film unit after development to terminate further dye transfer and thus stabilize the dye image. Such polymeric acids comprise polymers containing acid groups, such as carboxylic acid and sulfonic acid groups, which are capable of forming salts with alkali metals, such as sodium or potassium, or with organic bases particularly quaternary ammonium bases, such as tetramethyl ammonium hydroxide. The polymers can also contain potentially acid-yielding groups such as anhydrides or lactones or other groups which are capable of reacting with bases to capture and retain them. Generally the most useful polymeric acids contain free carboxyl groups, being insoluble in water in the free acid form and which form water-soluble sodium and/or potassium salts.

The polymeric acid layer is usually about 0.3 to about 1.5 mils in thickness. Although the polymeric layer is usually located in the receiver portion of the film unit between the support and the image-receiving layer, it can also be located in the negative portion of the film unit, as disclosed in U.S. Patent No. 3,362,821.

An inert timing or spacer layer coated over the polymeric acid layer may also be used to time or control the pH reduction of the film unit as a function of the rate at which the alkali diffuses through the inert spacer layer. Examples of such timing layers include gelatin, polyvinyl alcohol or any of those disclosed in U.S. Patent 3,455,686. The timing layer is also efiective in evening out the various reaction rates over a wide range of temperatures, e.g., premature pH reduction is prevented when imbibition is effected at temperatures above room temperature, for example, at 95 to 100 F. The timing layer is usually about 0.1 to about 0.7 mil in thickness.

The liquid processing composition employed in this invention is the conventional aqueous solution of an alkaline material, e.g., sodium hydroxide, sodium carbonate or an amine such as diethylamine, preferably possessing a pH in excess of 12. The solution also preferably contains a viscosity-increasing compound such as a high molecular weight polymer, e. g., a water-soluble ether inert to alkaline solutions such as hydroxyethyl cellulose or alkali metal salts of carboxymethyl cellulose such as sodium carboxymethyl cellulose. A concentration of viscosity-increasing compound of about 1 to about 5% by weight of the processing solution is preferred which will impart thereto a viscosity of about 100 cps. to about 200,000 cps.

Development of a diffusion transfer element of the invention may also be effected in the presence of an onium compound, particularly a quaternary ammonium compound, such as disclosed in U.S. Patents 3,146,102; 3,253,915 and 3,173,786.

The film support of the film assembly of this invention can be any material as long as it does not deleteriously aifect the photographic properties of the film unit and is dimensionally stable. Typical supports include cellulose nitrate film, cellulose acetate film, poly-(vinyl acetal) film, polystyrene film, poly(ethyleneterephthalate) film, polycarbonate film, poly-a-olefins such as polyethylene and polypropylene film, and related films or resinous materials as well as glass. The support layer is usually about 2 to 6 mils in thickness.

While the invention has been described with reference to layers of silver halide emulsions and dye image-providing materials, dotwise coating, such as would be obtained using a gravure printing technique, could also be employed. In this technique, small dots of blue, green and red-sensitive emulsions have associated therewith, respectively, dots of yellow, magenta and cyan color-providing substances. After development, the transferred dyes would tend to fuse together into a continuous tone.

The silver halide emulsions used with this invention can comprise silver chloride, silver bromide, silver bromoiodide, silver chlorobromoiodide or mixtures thereof. The emulsions may be coarse or fine grain and can be prepared by any of the well-known procedures, e.g. single jet emulsions, double jet emulsions, such as Lippmann emulsions, ammoniacal emulsions, thiocyanate or thioether ripened emulsions such as those described in Nietz et al. U.S. Patent 2,222,264; Illingsworth U.S. Patent 3,320,069; and McBride U.S. Patent 3,271,157. Surface image emulsions may be used or internal image emulsions such as those described in Davey et al. U.S. Patent 2,592,250; Porter et al. U.S. Patent 3,206,313; Berriman U.S. Patent 3,367,778 and Bacon et al. U.S. Patent 3,447,927. If desired, mixtures of surface and internal image emulsions may be used as described in Luckey et al. U.S. Patent 2,996,382. Negative type emulsions may be used or direct positive emulsions such as those described in Leermakers U.S. Patent 2,184,013; Kendall et al. U.S. Patent 2,541,- 472; Berriman U.S. Patent 3,367,778; Schouwenaars British Patent 723,019; lllingsworth et al. French Patent 1,520,821; Ives U.S. Patent 2,563,785; Knott et al. U.S. Patent 2,456,953 and Land U.S. Patent 2,861,885. The emulsions may be regular grain emulsions such as the 12 type described in Klein and Moisar, I. Phot. Sci., vol. 12, No. 5, September/October 1964, pp. 24225 1.

The silver halide emulsions used with this invention may be unwashed or washed to remove soluble salts. In the latter case the soluble salts may be removed by chillsetting and leaching or the emulsion may be coagulation washed, e.g. by the procedures described in Hewitson et al. U.S. Patent 2,618,556; Yutzy et al. U.S. Patent 2,614,- 928; Yackel U.S. Patent 2,565,418; Hart et al. U.S. Patent 3,241,969; and Waller et al. U.S. Patent 2,489,341.

The emulsions used with this invention may be sensitized with chemical sensitizers, such as with reducing agents; sulfur, selenium or tellurium compounds; gold, platinum or palladium compounds; or combinations of these. Suitable procedures are described in Sheppard et al. U.S. Patent 1,623,499; Waller et al. U.S. Patent 2,399,- 083; McVeigh U.S. Patent 3,297,447; and Dunn U.S. Patent 3,297,446.

The silver halide emulsions used with this invention may contain speed increasing compounds such as polyalkylene glycols, cationic surface active agents and thioethers or combinations of these as described in Piper U.S. Patent 2,886,437; Dann et al. U.S. Patent 3,046,134; Carroll et al. U.S. Patent 2,944,900; and Goffe U.S. Patent 3,294,540.

The silver halide emulsions used in the practice of this invention can be protected against the production of fog and can be stabilized against loss of sensitivity during keeping. Suitable antifoggants and stabilizers each used alone or in combination include thiazolium salts described in Brooker et al. U.S. Patent 2,131,038 and Allen et al. U.S. Patent 2,694,716; the azaindenes described in Piper U.S. Patent 2,886,437, and Heimbach et al. U.S. Patent 2,444,605; the mercury salts as described in Allen et al. U.S. Patent 2,728,663; the urazoles described in Anderson et al. U.S. Patent 3,287,135; the sulfocatechols described in Kennard et al. U.S. Patent 3,236,652; the oximes described in Carroll et al. British Patent 623,448; nitron; nitroindazoles; the mercaptotetrazoles described in Kendall et al. U.S. Patent 2,403,927; Kennard et al. U.S. Patent 3,266,897 and Luckey et al. U.S. Patent 3,397,987; the polyvalent metal salts described in Jones U.S. Patent 2,839,405; the thiuronium salts described in Herz et al. U.S. Patent 3,220,839; the palladium, platinum and gold salts described in Trivelli et al. U.S. Patent 2,566,263 and Yutzy et al. U.S. Patent 2,597,915.

The photographic and other hardenable layers used in the practice of this invention can be hardened by various organic or inorganic hardeners, alone or in combina tion, such as the aldehydes, and blocked aldehydes, ketones, carboxylic and carbonic acid derivatives, sulfonate esters, sulfonyl halides and vinyl sulfonyl ethers, active halogen compounds, expoxy compounds, aziridines, active olefins, isocyanates, carbodiimides, mixed function hardeners and polymeric hardeners such as oxidized polysaccharides like dialdehyde starch and oxyguargum and the like.

The photographic emulsions and elements described in the practice of this invention can contain various colloids alone or in combination as vehicles, binding agents and various layers. Suitable hydrophilic materials include both naturally-occurring substances such as proteins, for example, gelatin, gelatin derivatives, cellulose derivatives, polysaccharides such as dextran, gum arabic and the like; and synthetic polymeric substances such as water soluble polyvinyl compounds like poly(vinylpyrrolidone), acrylamide polymers and the like.

The described photographic emulsion layers and other layers of a photographic element employed in the practice of this invention can also contain alone or in combination with hydrophilic, water permeable colloids, other synthetic polymeric compounds such as dispersed vinyl compounds such as in latex form and particularly those which increase the dimensional stability of the photographic materials. Suitable synthetic polymers include those described, for example, in Nottorf US. Patent 3,142,568, issued July 28, 1964; White US. Patent 3,193,- 386, issued July 6, 1965; Houck et al. US. Patent 3,062,- 674, issued Nov. 6, 1962; Houck et al. US. Patent 3,220,844, issued Nov. 30, 1965; Ream et al. US. Patent 3,287,289, issued Nov. 22, 1966; and Dykstra US. Patent 3,411,911, issued Nov. 19, 1968; particularly effective are water-insoluble polymers of alkyl acrylates and methacrylates, acrylic acid, sulfoalkyl acrylates or methacrylates, those which have cross-linking sites which facilitate hardening or curing, and those having recurring sulfobetaine units as described in Dykstra Canadian Patent 774,054.

The photographic layers employed in the practice of this invention may contain surfactants such as saponin, anionic compounds such as the alkyl aryl sulfonates described in Baldsiefen US. Patent 2,600,831; a-mphoteric compounds such as those described in Ben-Ezra US. Patent 3,133,816; and water soluble adducts of glycidol and an alkyl phenol such as those described in Olin Mathieson British Patent 1,022,878.

The photographic elements used in this invention may contain brightening agents including stilbenes, triazines and oxazole brightening agents. Water soluble brightening agents may be used such as those described in Albers et al. German Patent 972,067 and McFall et al. US. Patent 2,933,390 or dispersions of brighteners may be used such as those described in Jansen German Patent 1,150,274, Oetiker et al. US. Patent 3,406,070 and Heidke French Patent 1,530,244.

The various layers, including the photographic layers, employed in the practice of this invention can contain light absorbing materials and filter dyes such as those described in Sawdey US. Patent 3,253,921; Gaspar US. Patent 2,274,782; Silberstein et al. US. Patent 2,527,583 and Van Campen US. Patent 2,956,879. If desired, the dyes can be mordanted, for example, as described in Milton et al. US. Patent 3,282,699.

The sensitizing dyes and other addenda used in the practice of this invention may be added from water solutions or suitable organic solvent solutions may be used. The compounds can be added using various procedures including those described in Collins et al. US. Patent 2,912,343; McCrossen et al. US. Patent 3,342,605; Audran US. Patent 2,996,287 and Johnson et a1. U.S. Patent 3,425,835.

The photographic layers used in the practice of this invention may be coated by various coating procedures including dip coating, air knife coating, curtain coating, or extrusion coating using hoppers of the type described in Beguin US. Patent 2,681,294. If desired, two or more layers may 'be coated simultaneously by the procedures described in Russell US. Patent 2,761,791 and Wynn British Patent 837,095. This invention also can be used for silver halide layers coated by vacuum evaporation as described in British Patent 968,453 and Lu Valle et al. US. Patent 3,219,451.

The following examples will illustrate the invention:

EXAMPLES l-S A photosensitive element is prepared by coating a subbed film support comprising cellulose acetate with suitably hardened gelatin layers as follows:

(1) Cyan dye developer layer The cyan dye developer 5,8-dihydroxy-1,4-bis[( S-hydroquinonyl-u-methyl)ethylamino1anthraquinone is dissolved in a mixture of N-n-butylacetanilide and 4-methyl cyclohexanone and dispersed in an aqueous gelatin solution with a sodium alkylnaphthalene sulfonate dispersing agent. The mixture is passed through a colloid mill several times, coated on the subbed support and dried so as to volatilize the 4-methyl cyclohexanone.

14 (2)Red-sensitive emulsion layer A gelatino silver bromoiodide emulsion layer, which is sensitized to the red region of the spectrum is coated upon the cyan dye developer layer.

(3) Interlayer A gelatin interlayer is then coated on the red-sensitive emulsion layer.

(4) Magenta dye developer layer The magenta dye developer 2- [p-(2",5"-dihydroxyphenethyl) phenylazo] 4-n-propoxy-1-naphthol is dissolved in a mixture of cyclohexanone and N-n-butylacetanilide and dispersed in an aqueous gelatin solution with a sodium alkylnaphthalene sulfonate dispersing agent. The mixture is passed through a colloid mill several times, coated on the interlayer and dried to volatilize the cyclohexanone.

(5) Green-sensitive emulsion layer A green-sensitive silver bromoiodide emulsion is coated on the magenta dye developer layer.

(6) Interlayer A second gelatin interlayer is coated onto the greensensitive emulsion layer.

(7) Yellow dye developer layer The yellow dye developer, 1-pheny1-3-N-n-hexy1carbamyl 4 [p-(2",5"-dihydroxyphenethyl)-phenylazo]-5- pyrazolone is dissolved in a mixture of ditetrahydrofurfuryl adipate and ethylene glycol monobenzyl ether and dispersed in an aqueous gelatin solution with a sodium alkylnaphthalene sulfonate dispersing agent. The mixture is passed through a colloid mill several times. The resulting dispersion is chilled to set it, washed to remove ethylene glycol monobenzyl ether followed by coating upon the second interlayer and drying.

(8) Blue-sensitive emulsion layer A blue-sensitive silver bromoiodide emulsion is coated onto the yellow dye developer layer.

(9) Overcoat layer Hydroxyethyl cellulose (HEC) 2.0 Sodium hydroxide 5.7 Sodium thiosulfate pentahydrate 0.4 Benzotriazole 2.4 1-benzyl-2-picolinium bromide 2.4 Water 87.1

The exposed film is processed at a gap of 0.004 inch (corresponding to the thickness of the activator layer) for a period of 60 seconds at 20 C. in contact with a color receiving sheet. The receiving sheet is a cellulose acetate butyrate subbed paper support carrying in the following order:

(1) a polymeric acid layer for pH control,

(2) a polyvinyl alcohol spacer layer,

( 3) a mordant layer comprising poly-4-vinyl pyridine and polyvinyl alcohol, and

(4) a polyvinyl alcohol protective layer.

The foregoing procedure is repeated with 4-methylphenylhydroquinone (control) and the various developing agent precursors set forth in Table 2 added to the processing solution in an amount of about 0.7% by weight. The following results are obtained:

TABLE 2 D mi 11.

Example Auxiliary developer or developer No. precursor Red Green Blue 1 35 60 60 2 4-methylphenylhydroqulnone (control). 32 49 50 3 6-an1lno-4,7-dlmethyl coumarin 24 41 41 4. fi-hydroxy-7-methoxy-4-methyl coumarin. 25 37 37 5. 6-hydroxy-4-niethyl coumarin 21 33 38 6- 6-hydroxy-4,7-dimethyl couma 21 34 34 7- 6-hydroxy-2-ket0-1.,4-benzoxathian. 24 40 47 8 -hydroxy-2-coumaranone 25 42 47 Examples 1, 2, 4 and 6 are repeated except that a calcium alginate barrier layer of the type described in Example IV of US. Pat. No. 3,384,483 is employed between (a) the red-sensitive silver halide emulsion layer and the magenta dye developer layer and (b) the green-sensitive silver halide emulsion layer and the yellow dye developer layer. The following results are obtained:

TABLE 3 min. Example Auxlliary developer or developer No. precursor Red Green Blue 9--- .24 .63 58 10- 4'-methylphenylhydroquinone (control). .30 38 .38 11 6-hydroxy-7-methoxy-4methyl coumarin. 19 36 37 12 6-hydroxy-4,7-dimethyl coumarim... 18 28 30 The above results illustrate the further improvement in D which may be obtained by employing a water-insoluble salt stratum, such as calcium alginate, between the photosensitive layers in the film unit.

The invention has been described with particular refer ence to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

I claim:

1. A photographic film unit which is adapted to be processed by passing said unit between a pair of juxtaposed pressure-applying members comprising:

(a) a photosensitive element comprising a support coated with at least one photosensitive silver halide emulsion layer, each said silver halide emulsion layer having associated therewith a dye image-providing material;

(b) a dye image-receiving layer; and

(c) a rupturable container containing an alkaline processing composition;

said film unit containing as an auxiliary silver halide de veloping agent a lactone developing agent precursor or a lactone derivative silver halide developing agent which has the property of forming a lactone developing agent precursor under acid, neutral and slightly alkaline conditions; said ruptura'ble container being adapted to be positioned so that a compressive force applied to said container by said pressure-applying members will effect a discharge of the containers contents into said film unit.

2. The film unit of claim 1 wherein said dye imagereceiving layer is located in said photosensitive element between said support and the lowermost photosensitive silver halide emulsion layer.

3. The film unit of claim 1 wherein said dye imagereceiving layer is coated on a separate support and is adapted to be superposed on said photosensitive element after exposure thereof.

4. The film unit of claim 3 wherein said rupturable container is so positioned in relation to said photosensitive element after exposure thereof and said dye image-receiving layer that a compressive force applied to said container by said pressure-applying members will effect a discharge of the containers contents between said dye imagereceiving layer and the outermost layer of said photosensitive element.

5. The film unit of claim 4 which contains said lactone derivative silver halide developing agent in said rupturable container.

6. The film unit of claim 5 wherein said lactone derivative is selected from the group consisting of coumarin derivatives, mixtures thereof and their salts.

7. The film unit of claim 6 wherein said coumarin derivative is a 6-hydroxy coumarin derivative or a 6- amino coumarin derivative.

8. The film unit of claim 1 wherein said lactone derivative silver halide developing agent is a cinnamic acid developing agent of the formula.

and said lactone developing agent precursor has the formula:

wherein (a) R and R are each hydrogen, halogen or alkyl of 1-5 carbon atoms;

(b) R and R are each hydrogen, halogen, alkyl of l-5 carbon atoms, alkoxy of l-S carbon atoms or aryl containing up to 20 carbon atoms;

(0) R and R are each hydroxy, amino, hydrogen, alkyl of 1-5 carbon atoms, alkoxy of l-5 carbon atoms or aryl containing up to 20 carbon atoms.

9. The film unit of claim 5 wherein said lactone derivative silver halide developing agent is a cinnarnic acid developin g agent of the formula:

wherein:

(a) R and R are each hydrogen, halogen or alkyl of l-S carbon atoms;

(b) R and R are each hydrogen, halogen, alkyl of 1-5 carbon atoms, alkoxy of l-5 carbon atoms or aryl containing up to 20 carbon atoms;

(c) R, and R are each hydroxy, amino, hydrogen, alkyl of 1-5 carbon atoms, alkoxy of 1-5 carbon atoms or aryl containing up to 20 carbon atoms.

10. The film unit of claim 1 wherein said photosensitive element comprises a support coated with a cyan dye image-providing material layer, a red-sensitive silver halide emulsion layer, a magenta dye image-providing material layer, a green-sensitive silver halide emulsion layer, a yellow dye image-providing material layer and a b uesensitive silver halide emulsion layer.

11. The film unit of claim 10 wherein each said dye image-providing material is a dye developer which is both a silver halide developing agent and a dye, contiguous to the silver halide of each silver halide emulsion layer.

12. The film unit of claim wherein said photosensitive element comprises a support coated with a cyan dye image-providing material layer, a red-sensitive silver halide emulsion layer, a magenta dye image-providing material layer, a green-sensitive silver halide emulsion layer, a yellow dye image-providing material layer and a blue sensitive silver halide emulsion layer.

13. The film unit of cla'nn 12 wherein each said dye image-providing material is a dye developer which is both a silver halide developing agent and a dye, contiguous to the silver halide of each silver halide emulsion layer.

14. The film unit of claim 13 wherein a water-insoluble salt stratum is positioned between the red-sensitve silver halide emulsion layer and the magenta dye developer layer and also between the green-sensitive silver halide emulsion layer and the yellow dye developer layer.

15. The film unit of claim 9 wherein said photosensitive element comprises a support coated with a cyan dye image-providing material layer, a red-sensitive silver halide emulsion layer, a magenta dye image-providing material layer, a green-sensitive silver halide emulsion layer, a yellow dye image-providing material layer and a bluesensitive silver halide emulsion layer.

16. The film unit of claim 15 wherein each said dye image-providing material is a dye developer which is both a silver halide developing agent and a dye, contiguous to the silver halide of each silver halide emulsion layer.

17. The film unit of claim 16 wherein a water-insoluble salt stratum is positioned between the'red-sensitive silver halide emulsion layer and the magenta dye developer layer and also between the green-sensitive silver halide emulsion layer and the yellow dye developer layer.

18. The film unit of claim 17 wherein said water-insoluble salt stratum is calcium alginate.

19. A photographic film unit which is adapted to be processed by passing said unit between a pair of juxtaposed pressure-applying members comprising:

(a) a photosensitive element comprising a support coated with a cyan dye developer layer, a red-sensitive silver halide emulsion layer, a magenta dye developer layer, a green-sensitive silver halide emulsion layer, a yellow dye developer layer, and a bluesensitive silver halide emulsion layer;

(b) an image-receiving layer coated on a support and adapted to be superposed over said blue-sensitive silver halide emulsion layer after exposure of said photosensitive element; and

(c) a rupturable container which is adapted to be positioned between said photosensitive element after exposure thereof and said receiving layer so that a compressive force applied to said container by said pressure-applying members will eifect a discharge of the containers contents between said image-receiving layer and said outermost layer of said photosensitive element, said rupturable container containing an alkaline processing composition and as an auxiliary silver halide developing agent a lactone derivative silver halide developing agent selected from the group consisting of coumarin derivatives, mixtures thereof and their salts.

ver halide emulsion layers;

(d) forming an imagewise distribution of diifusible dye image-providing material as a function of said imagewise exposure of each of said silver halide emulsion layers; and

(e) at least a portion of each of said imagewise distributions of difiusible dye image-providing material diffusing to an image-receiving layer;

said development being effected in the presence of an auxiliary silver halide development agent comprising a lactone derivative silver halide developing agent which has the property of forming a lactone developing agent precursor under acid, neutral and slightly alkaline conditions.

21. The process of claim 20 wherein said treatment step (b) is effected by (a) superposing an image-receiving layer coated on a support over the layer outermost from the support of said photosensitive element;

(b) positioning a rupturable container containing an alkaline processing composition between said exposed photosensitive element and said image-receiving layer; and

(c) applying a compressive force to said container to effect a discharge of the containers contents between said outermost layer of said exposed photosensitive element and said image-receiving layer.

22. The process of claim 21 wherein said lactone derivative is selected from the group consisting of coumarin derivatives, mixtures thereof and their salts.

23. The process of claim 22 wherein said coumarin derivative is a 6-hydroxy coumarin derivative or a 6-amino coumarin derivative.

24. The process of claim 21 wherein said lactone derivative silver halide development agent is a cinnamic acid developing agent of the formula:

5O Ra R R R4 (|J=(|JCOOH R5- -OH 1 wherein: (a) R and R are each hydrogen, halogen or alkyl of 15 carbon atoms;

(b) R and R are each hydrogen, halogen, alkyl of 1-5 carbon atoms, alkoxy of 1-5 carbon atoms or aryl containing up to 20 carbon atoms;

(c) R; and R are each hydroxy, amino, hydrogen, alkyl of 1-5 carbon atoms, alkoxy of 1-5 carbon atoms or aryl containing up to 20 carbon atoms.

25. The process of claim 24 wherein said photosensitive element comprises a support coated with a cyan dye image-providing material layer, a red-sensitive silver halide emulsion layer, a magenta dye image-providing material layer, a green-sensitive silver halide emulsion layer, a yellow dye image-providing material layer and a bluesensitive silver halide emulsion layer.

19 20 26. The process of claim 25 wherein each said dye References Cited image-providing material is a dye developer which is both UNITED STATES PATENTS a. silver halide developing agent and a dye, contiguous to the silver halide of each silver halide emulsion layer. 2,685,515 8/1954 Wflson 96 66-3X 27. The process of claim 26 wherein a water-insoluble salt stratum is positioned between the red-sensitive silver 5 NORMAN TORCHIN Pnmary Exammer halide emulsion layer and the magenta dye developer A. T. SURO PICO, Assistant Examiner layer and also between the green-sensitive silver halide emulsion layer and the yellow dye developer layer. US. Cl. X.R.

28. The process of claim 27 wherein said water-insol- 1O 9666.3 uble salt stratum is calcium alginate. 

